linux/arch/sh/kernel/ptrace.c
Stuart Menefy 9432f96803 sh: Clear UBC when not in use.
This takes care of tearing down the UBC so it's not inadvertently
left configured at the next context switch time. Failure to do
this results in spurious SIGTRAPs in certain debug sequences.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-03-05 14:13:25 +09:00

291 lines
6.8 KiB
C

/*
* linux/arch/sh/kernel/ptrace.c
*
* Original x86 implementation:
* By Ross Biro 1/23/92
* edited by Linus Torvalds
*
* SuperH version: Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
*
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <linux/io.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu_context.h>
/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.
*/
/*
* This routine will get a word off of the process kernel stack.
*/
static inline int get_stack_long(struct task_struct *task, int offset)
{
unsigned char *stack;
stack = (unsigned char *)task_pt_regs(task);
stack += offset;
return (*((int *)stack));
}
/*
* This routine will put a word on the process kernel stack.
*/
static inline int put_stack_long(struct task_struct *task, int offset,
unsigned long data)
{
unsigned char *stack;
stack = (unsigned char *)task_pt_regs(task);
stack += offset;
*(unsigned long *) stack = data;
return 0;
}
static void ptrace_disable_singlestep(struct task_struct *child)
{
clear_tsk_thread_flag(child, TIF_SINGLESTEP);
/*
* Ensure the UBC is not programmed at the next context switch.
*
* Normally this is not needed but there are sequences such as
* singlestep, signal delivery, and continue that leave the
* ubc_pc non-zero leading to spurious SIGTRAPs.
*/
if (child->thread.ubc_pc != 0) {
ubc_usercnt -= 1;
child->thread.ubc_pc = 0;
}
}
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure single step bits etc are not set.
*/
void ptrace_disable(struct task_struct *child)
{
ptrace_disable_singlestep(child);
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
struct user * dummy = NULL;
int ret;
switch (request) {
/* when I and D space are separate, these will need to be fixed. */
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA: {
unsigned long tmp;
int copied;
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
ret = -EIO;
if (copied != sizeof(tmp))
break;
ret = put_user(tmp,(unsigned long *) data);
break;
}
/* read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
unsigned long tmp;
ret = -EIO;
if ((addr & 3) || addr < 0 ||
addr > sizeof(struct user) - 3)
break;
if (addr < sizeof(struct pt_regs))
tmp = get_stack_long(child, addr);
else if (addr >= (long) &dummy->fpu &&
addr < (long) &dummy->u_fpvalid) {
if (!tsk_used_math(child)) {
if (addr == (long)&dummy->fpu.fpscr)
tmp = FPSCR_INIT;
else
tmp = 0;
} else
tmp = ((long *)&child->thread.fpu)
[(addr - (long)&dummy->fpu) >> 2];
} else if (addr == (long) &dummy->u_fpvalid)
tmp = !!tsk_used_math(child);
else
tmp = 0;
ret = put_user(tmp, (unsigned long *)data);
break;
}
/* when I and D space are separate, this will have to be fixed. */
case PTRACE_POKETEXT: /* write the word at location addr. */
case PTRACE_POKEDATA:
ret = 0;
if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
break;
ret = -EIO;
break;
case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
ret = -EIO;
if ((addr & 3) || addr < 0 ||
addr > sizeof(struct user) - 3)
break;
if (addr < sizeof(struct pt_regs))
ret = put_stack_long(child, addr, data);
else if (addr >= (long) &dummy->fpu &&
addr < (long) &dummy->u_fpvalid) {
set_stopped_child_used_math(child);
((long *)&child->thread.fpu)
[(addr - (long)&dummy->fpu) >> 2] = data;
ret = 0;
} else if (addr == (long) &dummy->u_fpvalid) {
conditional_stopped_child_used_math(data, child);
ret = 0;
}
break;
case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
case PTRACE_CONT: { /* restart after signal. */
ret = -EIO;
if (!valid_signal(data))
break;
if (request == PTRACE_SYSCALL)
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
else
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
ptrace_disable_singlestep(child);
child->exit_code = data;
wake_up_process(child);
ret = 0;
break;
}
/*
* make the child exit. Best I can do is send it a sigkill.
* perhaps it should be put in the status that it wants to
* exit.
*/
case PTRACE_KILL: {
ret = 0;
if (child->exit_state == EXIT_ZOMBIE) /* already dead */
break;
ptrace_disable_singlestep(child);
child->exit_code = SIGKILL;
wake_up_process(child);
break;
}
case PTRACE_SINGLESTEP: { /* set the trap flag. */
long pc;
struct pt_regs *dummy = NULL;
ret = -EIO;
if (!valid_signal(data))
break;
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
if ((child->ptrace & PT_DTRACE) == 0) {
/* Spurious delayed TF traps may occur */
child->ptrace |= PT_DTRACE;
}
pc = get_stack_long(child, (long)&dummy->pc);
/* Next scheduling will set up UBC */
if (child->thread.ubc_pc == 0)
ubc_usercnt += 1;
child->thread.ubc_pc = pc;
set_tsk_thread_flag(child, TIF_SINGLESTEP);
child->exit_code = data;
/* give it a chance to run. */
wake_up_process(child);
ret = 0;
break;
}
case PTRACE_DETACH: /* detach a process that was attached. */
ret = ptrace_detach(child, data);
break;
#ifdef CONFIG_SH_DSP
case PTRACE_GETDSPREGS: {
unsigned long dp;
ret = -EIO;
dp = ((unsigned long) child) + THREAD_SIZE -
sizeof(struct pt_dspregs);
if (*((int *) (dp - 4)) == SR_FD) {
copy_to_user(addr, (void *) dp,
sizeof(struct pt_dspregs));
ret = 0;
}
break;
}
case PTRACE_SETDSPREGS: {
unsigned long dp;
ret = -EIO;
dp = ((unsigned long) child) + THREAD_SIZE -
sizeof(struct pt_dspregs);
if (*((int *) (dp - 4)) == SR_FD) {
copy_from_user((void *) dp, addr,
sizeof(struct pt_dspregs));
ret = 0;
}
break;
}
#endif
default:
ret = ptrace_request(child, request, addr, data);
break;
}
return ret;
}
asmlinkage void do_syscall_trace(void)
{
struct task_struct *tsk = current;
if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
!test_thread_flag(TIF_SINGLESTEP))
return;
if (!(tsk->ptrace & PT_PTRACED))
return;
/* the 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
!test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
/*
* this isn't the same as continuing with a signal, but it will do
* for normal use. strace only continues with a signal if the
* stopping signal is not SIGTRAP. -brl
*/
if (tsk->exit_code) {
send_sig(tsk->exit_code, tsk, 1);
tsk->exit_code = 0;
}
}